This application claims priority to International Application No. PCT/GB99/04111 filed Dec. 6, 1999, which was published on Jun. 29, 2000.
The invention relates to a vacuum cleaner. Particularly, the invention relates to a vacuum cleaner having a chassis, supporting wheels mounted on the chassis, drive means connected to the supporting wheels for driving the supporting wheels, a control mechanism for controlling the drive means so as to guide the vacuum cleaner across a surface to be cleaned, a cleaner head having a dirty air inlet facing the surface to be cleaned, and separating apparatus supported by the chassis and communicating with the cleaner head for separating dirt and dust from an airflow entering the vacuum cleaner by way of the dirty air inlet. Such a vacuum cleaner is more conveniently termed a robotic vacuum cleaner.
Robotic vacuum cleaners are known. The control mechanism normally includes sensors for detecting obstacles and walls so that the vacuum cleaner is capable of guiding itself around a room so as to vacuum the carpet or other floor covering without human intervention. Examples of robotic vacuum cleaners of this general type are shown and described in, inter alia, EP0803224A, U.S. Pat. No. 5,534,762, W097/41451, U.S. Pat. No. 5,109,566 and U.S. Pat. No. 5,787,545. In the prior art cleaners, the separating apparatus by means of which the dirt and dust is separated from the airflow consists of a bag-type filter or an equivalent container-type filter. The difficulty with arrangements such as these is that, as the bag fills, it becomes clogged with dirt and dust so that the ability of the cleaner to pick up dirt and dust reduces with time. This means that the performance of the cleaner does not remain at a constant standard during operation and may require human intervention to compensate for the reduction in performance. This defeats the object of a robotic vacuum cleaner.
It is an object of the present invention to provide a robotic vacuum cleaner which does not clog as the dirt and dust are separated from the airflow. It is another object of the invention to provide a robotic vacuum cleaner whose pick-up capability does not diminish over time. It is a further object of the invention is to provide a robotic vacuum cleaner which is simple to use and effective in its operation without being prohibitively expensive to manufacture.
The invention provides a vacuum cleaner having a chassis, supporting wheels mounted on the chassis, drive means connected to the supporting wheels for driving the supporting wheels, a control mechanism for controlling the drive means so as to guide the vacuum cleaner across a surface to be cleaned, a cleaner head having a dirty air inlet facing the surface to be cleaned, and separating apparatus supported by the chassis and communicating with the cleaner head for separating dirt and dust from an airflow entering the vacuum cleaner by way of the dirty air inlet, characterised in that the separating apparatus comprises at least one cyclone.
Providing cyclonic separating apparatus on a robotic vacuum cleaner removes the problem of the bag- or container-type filters clogging with use. In cyclonic separating apparatus, clogging does not occur and therefore there is no decrease in the pick-up capability which maintains the suction at the dirty air inlet. The performance of the cleaner remains constant because the suction developed at the dirty air inlet is maintained at a constant level.
Preferably, the separating apparatus comprises two cyclones, the upstream cyclone being adapted to remove comparatively large dirt and dust particles from the airflow and the downstream cyclone being adapted to remove comparatively small dirt and dust particles from the airflow. This arrangement allows the downstream cyclone to operate under optimum conditions because the larger dirt and dust particles have already been removed from the airflow before it reaches the downstream, high efficiency cyclone. It is also preferred if the cyclones are arranged concentrically, more preferably one inside the other, so as to provide a compact and convenient arrangement. In this case, the outer, low efficiency cyclone can be generally cylindrical in shape and the inner, high efficiency cyclone can be frusto-conical in shape.
Preferably, the separating apparatus is supported on the chassis with the longitudinal axis of the separating apparatus lying in a substantially horizontal position. This minimises the height of the cleaner.
The cyclonic separating apparatus preferably includes a removable bin or collecting chamber in which, in use, the dirt and dust separated from the airflow is collected. The bin or collecting chamber is removable to allow convenient emptying of the vacuum cleaner of dirt and dust. It is preferable if the bin or collecting chamber is transparent or translucent so that the interior of the bin or collecting chamber can be periodically inspected. The user can then see when the bin needs to be emptied.